In conventional movements, it is known to use a system of two coaxial wheels with a coupling by means of a spring fixed to the first wheel and pressing radially on a third wheel integral with the second wheel. The known coupling system therefore essentially has three levels and provides a jumper spring that acts radially on a toothing of a third wheel. To overcome this radial elastic force, a disengagement torque must be exerted on one of the two wheels while the other has a sufficiently high reaction torque to permit application of said disengagement torque. The third toothed wheel defines a plurality of discrete relative angular positions for the two wheels. Provided the relative torque between the two wheels is lower than the disengagement torque, the two wheels rotate integrally. Applying a disengagement torque between the two wheels changes the relative angular position by a desired number of steps. This construction takes up a relatively large amount of space as the spring generally has lobes which occupy a large surface area to achieve the required elastic properties. Further, this construction is complex and fragile because the shape of the spring is relatively complex and the spring has a thin section to achieve the aforementioned required elastic properties. Furthermore, the diameter of the third wheel is limited by the space required to mount the radially acting spring, which limits the number of jump steps in one complete revolution.